DIY CNC router - Original design - Router Forums
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post #1 of 23 (permalink) Old 05-16-2017, 12:11 PM Thread Starter
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Default DIY CNC router - Original design

I recently built my own CNC router. With the recent discussions of the 4' x 4' CNC Router parts and Fine Line Automation Saturn machines, I thought that some may be interested in a similarly sized DIY machine not built from a kit. I was in the same position of some of you and could not afford an assembled or even kit based machine.

My machine has a cutting area of 49" x 60", and It is designed so that I can hold a full sheet of MDF or Melamine (at 49" x 97" they are slightly larger than plywood sheets). It is relatively easy to index what you are cutting and slide the sheet to work with stock larger than your nominal cutting area. If my shop was big enough I would have made it long enough to handle the full sheet without indexing. That said, most of the projects I foresee making will be easily accommodated by the size it is without indexing.

My router is made from two sizes of 8020 brand extrusions, 80x160mm (which is the biggest 8020 makes, I believe) and 80x80mm, along with some flat and angle stock. These extrusions are extremely stout and larger than I have seen in most kits. I lucked into buying this as surplus and got it at a bargain price, $1 per pound - normally these size extrusions would go for $2- $3 per inch. Bargain hunting is key to saving money on DIY builds! All of my frame and structural materials came out to a little less than $600, maybe another $100 in fasteners. The extrusions would cost about $2500 to buy new at 8020's online prices (not including shipping).

The machine weighs more than 400 pounds, and is built almost entirely of aluminum. Most parts I used at the size I found at the surplus yard. I did not need to have any parts machined - any cuts needed were cut by me using standard woodworking tools such as a radial arm saw and a drill press. Most assembly holes were match drilled with a handheld drill.

My CNC router is my own design and has several unique features. While it normally has 5" clear between spoil board and lowest point on gantry, it is designed so the entire gantry can be easily raised steplessly to provide clearance up to 12 inches. I know of no other designs with this engineered-in flexibility in gantry height. My Z axis has 7" of travel, with a bit projecting 2" from collet, I can raise the end of the bit flush with bottom of gantry. It also has a very unique Y-Z carriage design that maximizes the spacing of the bearing assemblies and minimizes the cantilever of the spindle. Instead of heavy plates it is all made from very stiff yet light aluminum angle. My unique design avoids the large spindle cantilever I see as a weakness in virtually every commercial machine. My spindle axis is only about 3" from the gantry.

Electronics wise I used good, but definitely not industrial grade components - ethernet smoothstepper, Gecko G540 stepper driver, low inductance 420 oz in NEMA 23 steppers (4) from CNC Router Parts. I used fully supported SBR type linear guides all around, rack and pinion for X and Y axis and a ballscrew for Z. I have tested it up to 1000 ipm rapids (I have it set in Mach at 600 which is plenty fast enough for me). My normal cutting speeds are usually in the 180 - 200 ipm range. It has a 2.2kw water cooled spindle, with the computer starting, stopping and controlling spindle speed via g-code (via PWM 0-10V control using the G540, no modbus needed).

My electronics are all mounted to the back side of the gantry - no complicated cable chains - far shorter wiring runs and no damage to cable due to repetitive flexing. I see so many people with complicated electronics, my box is only about 15 x 4 x 8. It has a plexiglas cover so I can see all the status LEDs. Even my VFD is mounted to the gantry. A single Ethernet cable runs from the computer to the cnc, run up the wall, across ceiling and down to the gantry with enough slack to cover travel range.

Software wise, I use Mach4 as the control software ($200). Mach3 is more widely used and well supported, but is basically end of life. Mach4 is fully functional now and still being actively developed. If I had heard of UCCNC before setting up the computer, I probably would have gone with that. Several people I respect on CNCZONE recommend it and it is cheaper ($60).

While I have quite a few friends using various Vectric software titles, and they are good, Vectric is not the only game in town. It was too pricey for my budget. Autodesk Fusion 360 is a full 3d CAD package (including CAM to generate your g-code!) that is available FREE to students OR startups (including hobbyists) making less than $100k per year. Far more capable than sketchup, (even the Pro version) it is a great bargain. I use it for mechanical type designs.

Autodesk ran a one day special at the end of January and I got a full year of ArtCAM Standard for $99! While I hate "renting" software, the low entry price for near Aspire level capabilities made it a no brainer. They currently (thru July 31, 2017) have it at $180 for a year. I use ArtCAM for artistic type projects.

ArtCAM and Fusion 360 run on a separate, more powerful computer in the house. Gcode file are transferred via USB stick - the cnc control computer is not online to preclude unwanted updates or interruptions.

All in, I only spent about $2700 on my machine, including the brand new HP all in one computer with Windows 10 (dedicated only to running Mach4 to operate CNC) and software. It is fast, strong, and I understand every part of it. I think it is stronger, and faster than the $18,000 Legacy Maverick that several people I know have (it does not yet have the rotary axis of the Maverick, but it will!). I purposely built it bigger than the Maverick which only does 36" x 60", just to have bragging rights over my friends.

I would recommend building your own machine, if and only if, building it would be an enjoyable project on its own for you. For me it was, and due to getting some bargains, I ended up with a far better machine for the price than I have seen anywhere, so it definitely can be a good way to go. From what I have seen out there, even if I bought the extrusions new, my machine would compete price and performance wise with anything of similar size.

Perhaps @Rainman 2.0 could build the all aluminum router he'd like AND insulate the shop - the extrusions I bought are still available in Northern Colorado - not too far of a drive to save a couple thousand $. The supplier is motion control surplus - they are also a hiwin distributor - pick up your guide rails in person at the same time and save a lot on shipping.

I welcome any questions or feedback.

Richard
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post #2 of 23 (permalink) Old 05-16-2017, 06:19 PM
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That looks very nice, Richard, and welcome to the forum! I built the first Saturn 2x4 that Nate had to offer at FLA and it's quite a hefty machine. But you definitely simplified things with your electronics and such. Nice job!

What do you make/build, primarily?

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post #3 of 23 (permalink) Old 05-16-2017, 07:54 PM
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Great post Richard , and congrats on making such a heavy duty machine at such a reasonable price .
You certainly scored when you sourced the aluminum extrusion, wow!
I see I made the post too lol .

I am liking the idea of building your own CNC . I would cheat in a few areas , like buy the Z axis already assembled .
I'm wanting to go with linear rails , those block type style like there now using at CNCrouterparts on there Pro version . But I would like to go with larger extruded aluminum on the Y axis as you did .
Thanks for posting , that's a great looking machine

I donít always insulate , but when I do .
Ok ,I never insulate
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post #4 of 23 (permalink) Old 05-16-2017, 08:01 PM
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Richard , do you have and profile shots of your rack and pinion drives on the Y axis ? I can't get a good look at how you designed it , or if there directly connected to gear rack ?
I was going to buy CNCrouterparts pro version rack and pinion if I end up building one .

I'm also liking the front hinged spoil board idea . Very clever

I donít always insulate , but when I do .
Ok ,I never insulate
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post #5 of 23 (permalink) Old 05-16-2017, 09:43 PM Thread Starter
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David - I make all kinds of things, just a hobbyist. I plan on making another rocker like this one. Hoping to start making a little money selling signs and carvings.

I also like making jigs and tools. Today I was working on soap cutter for my daughter-in-law. Cut this aluminum on the router. 3/8 thick, using 1/8 2 flute carbide cutter (one of my $4.00 bits from eBay seller Drillman1). 30 ipm, .06 depth of cut. This is the kind of thing I use Fusion 360 for. Router handled it just fine.

Rick - I do use direct drive. My gantry beam is about 60 pounds, all together the gantry probably is around 85 pounds. According to my calculations, the two steppers on X can easily move it, and accelerate it pretty well. I used the round linear rails as they are far cheaper than the profile rails. The profile rails are much stronger and stiffer, but in my opinion are overkill for a hobbyist machine. The SBR bearings I used are rated at 385 lbs each, there are 4 supporting the 85 pound gantry, well spaced apart. The profile rails have ratings in the thousands of pound range. I have done enough hand routing to know that there is no way that the loads imparted by a router bit cutting wood (or even aluminum) are going to overload my linear bearing. The YZ carriage is maybe 20 pounds (the spindle and stepper are the heaviest items), and the single stepper can easily move and accelerate it. You'll notice that the steppers are very near the items they are moving, the Y stepper for example is at the bottom, near the bit.

The way may machine is designed, all 4 steppers are mounted on gantry, which is why I decided to put the electronics there as well. The three home switches are also on the gantry (triggered by a piece of structure). I do not use limit switches, but do have mechanical stops to prevent the gantry or YZ carriage from over travel.
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post #6 of 23 (permalink) Old 05-16-2017, 09:58 PM Thread Starter
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The hinged table is still a bit of a work in progress - I need to add some stiffeners on the back side to keep it straight, and figure out how to handle clamping boards to it. I will probably go with some rectangular cutouts like @4DThinker uses on his tilting table. It does pivot from vertical to horizontal. The spindle can actually reach almost 6 inches past where the fixed table ends. I will be able to work on the ends of fairly large and wide pieces.

By the way, my rack and pinions came from McMaster Carr - best price I could find. Bought 3 6-foot racks (20 pitch, 20˚ pressure angle and matching pinions.

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post #7 of 23 (permalink) Old 05-16-2017, 10:18 PM
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Thanks for the info Richard . I have to say I'm very impressed by this build and your talent , and I like how you think out of the box

I donít always insulate , but when I do .
Ok ,I never insulate
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post #8 of 23 (permalink) Old 05-16-2017, 10:36 PM
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Richard , I think the electronics being mounted on the gantry has its advantages, but my concern would be the potential of getting a cold solder joint in the electronics from long term vibration .
I'm not an optimistic, so maybe I worry to much sometimes.

I was wondering how you get the proper engagement on the gear rack from the pinion on the stepper motors on the Y axis . Are the holes elongated where the steppers are mounted in order to rotate it to put the appropriate pressure on the gear rack ?
The reason I ask is , if there's not perfect engagement there would be the potential for backlash , which would obviously cause poor repeatability.
I've noticed most systems have a spring that can be tensioned to get the right pressure between the stepper motors pinion to gear rack contact

I donít always insulate , but when I do .
Ok ,I never insulate

Last edited by RainMan 2.0; 05-16-2017 at 10:45 PM.
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post #9 of 23 (permalink) Old 05-16-2017, 10:44 PM
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One other question lol .
When the pinion on the stepper spins , in theory it would try and climb out of the gear rack .
Of course it doesn't , because the bearings on the rail are holding it true , but I've noticed that the weakest part of the bearing (the bottom) would be taking the brunt of the force from this stepper as it's creating torque .
Not sure without firing up photoshop and illustrating this , that my concern makes any sense .
I'm sure I'm overthinking this , but I think the gear rack should be mounted so that the stepper puts force the other direction, pulls the gantry down , not forcing it up .
Like if the gear rack was mounted above the steppers pinion , not above it?

But I do love the simplicity of your design

I donít always insulate , but when I do .
Ok ,I never insulate

Last edited by RainMan 2.0; 05-16-2017 at 10:51 PM.
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post #10 of 23 (permalink) Old 05-16-2017, 10:56 PM
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I sure do like the CNC as you've built it. The only small thing my "what if" mind worries about is that wood chips may land atop the side toothed rack and jam up the Y movement. When I'm cutting up and down the grain of hardwoods it is not unusual for large wood sections to split off before being chewed up by the router bit. Big enough to clog up the 2" hose of my dust collector.

In addition to holes for clamps cut into your tilting table section you may want to reinforce/stiffen that MDF panel. I've use furniture grade plywood for mine and they occasionally deflect/warp when clamping down boards that have their own warp or twist.

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